Upper limit on the cosmic-ray photon flux above 10^19 eV using the surface detector of the Pierre Auger Observatory

ArXiv 0712.1147 (2007)

Abstract:

A method is developed to search for air showers initiated by photons using data recorded by the surface detector of the Auger Observatory. The approach is based on observables sensitive to the longitudinal shower development, the signal risetime and the curvature of the shower front. Applying this method to the data, upper limits on the flux of photons of 3.8*10^-3, 2.5*10^-3, and 2.2*10^-3 km^-2 sr^-1 yr^-1 above 10^19 eV, 2*10^19 eV, and 4*10^19 eV are derived, with corresponding limits on the fraction of photons being 2.0%, 5.1%, and 31% (all limits at 95% c.l.). These photon limits disfavor certain exotic models of sources of cosmic rays. The results also show that the approach adopted by the Auger Observatory to calibrate the shower energy is not strongly biased by a contamination from photons.

Heterotic string compactifications on half-flat manifolds II

Journal of High Energy Physics 2007:12 (2007)

Authors:

S Gurrieri, A Lukas, A Micu

Abstract:

In this paper, we continue the analysis of heterotic string compactifications on half-flat mirror manifolds by including the 10-dimensional gauge fields. It is argued, that the heterotic Bianchi identity is solved by a variant of the standard embedding. Then, the resulting gauge group in four dimensions is still E 6 despite the fact that the Levi-Civita connection has SO(6) holonomy. We derive the associated four-dimensional effective theories including matter field terms for such compactifications. The results are also extended to more general manifolds with SU(3) structure. © SISSA 2007.

Sparticle spectra from Large‐Volume String Compactifications

AIP Conference Proceedings AIP Publishing 957:1 (2007) 201-204

Authors:

Joseph P Conlon, Arttu Rajantie, Carlo Contaldi, Paul Dauncey, Horace Stoica

The closed string spectrum of SU (N) gauge theories in 2 + 1 dimensions

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 656:1-3 (2007) 132-140

Authors:

A Athenodorou, B Bringoltz, M Teper

Abstract:

We use lattice techniques to study the closed-string spectrum of SU (N) gauge theories in 2 + 1 dimensions. We calculate the energies of the lowest lying ∼30 states for strings with lengths between l ∼ 0.45  fm and l ∼ 3  fm, and compare to different theoretical predictions. We obtain unambiguous evidence that the closed-strings are in the universality class of the Nambu-Goto free bosonic string. Moreover, we clearly see that our data can be described by a covariant string theory with a small/moderate correction down to very short distance scales, and possibly on all distance scales at large-N. © 2007 Elsevier B.V. All rights reserved.

Correlation of the highest-energy cosmic rays with nearby extragalactic objects.

Science 318:5852 (2007) 938-943

Authors:

Pierre Auger Collaboration, J Abraham, P Abreu, M Aglietta, C Aguirre, D Allard, I Allekotte, J Allen, P Allison, C Alvarez, J Alvarez-Muñiz, M Ambrosio, L Anchordoqui, S Andringa, A Anzalone, C Aramo, S Argirò, K Arisaka, E Armengaud, F Arneodo, F Arqueros, T Asch, H Asorey, P Assis, BS Atulugama, J Aublin, M Ave, G Avila, T Bäcker, D Badagnani, AF Barbosa, D Barnhill, SLC Barroso, P Bauleo, J Beatty, T Beau, BR Becker, KH Becker, JA Bellido, S Benzvi, C Berat, T Bergmann, P Bernardini, X Bertou, PL Biermann, P Billoir, O Blanch-Bigas, F Blanco, P Blasi, C Bleve, H Blümer, M Bohácová, C Bonifazi, R Bonino, M Boratav, J Brack, P Brogueira, WC Brown, P Buchholz, A Bueno, NG Busca, KS Caballero-Mora, B Cai, DV Camin, R Caruso, W Carvalho, A Castellina, O Catalano, G Cataldi, L Cazón-Boado, R Cester, J Chauvin, A Chiavassa, JA Chinellato, A Chou, J Chye, PDJ Clark, RW Clay, E Colombo, R Conceição, B Connolly, F Contreras, J Coppens, A Cordier, U Cotti, S Coutu, CE Covault, A Creusot, J Cronin, S Dagoret-Campagne, K Daumiller, BR Dawson, RM de Almeida, C De Donato, SJ de Jong, G De La Vega, WJM de Mello Junior, JRT de Mello Neto, I De Mitri, V de Souza, L Del Peral, O Deligny, A Della Selva, C Delle Fratte, H Dembinski, C Di Giulio, JC Diaz, C Dobrigkeit, JC D'Olivo, D Dornic, A Dorofeev, JC Dos Anjos, MT Dova, D D'Urso, MA Duvernois, R Engel, L Epele, M Erdmann, CO Escobar, A Etchegoyen, P Facal San Luis, H Falcke, G Farrar, AC Fauth, N Fazzini, A Fernández, F Ferrer, S Ferry, B Fick, A Filevich, A Filipcic, I Fleck, R Fonte, CE Fracchiolla, W Fulgione, B García, D García Gámez, D Garcia-Pinto, X Garrido, H Geenen, G Gelmini, H Gemmeke, PL Ghia, M Giller, H Glass, MS Gold, G Golup, F Gomez Albarracin, M Gómez Berisso, R Gómez Herrero, P Gonçalves, M Gonçalves do Amaral, D Gonzalez, JG Gonzalez, M González, D Góra, A Gorgi, P Gouffon, V Grassi, A Grillo, C Grunfeld, Y Guardincerri, F Guarino, GP Guedes, J Gutiérrez, JD Hague, JC Hamilton, P Hansen, D Harari, S Harmsma, JL Harton, A Haungs, T Hauschildt, MD Healy, T Hebbeker, D Heck, C Hojvat, VC Holmes, P Homola, J Hörandel, A Horneffer, M Horvat, M Hrabovsky, T Huege, M Iarlori, A Insolia, F Ionita, A Italiano, M Kaducak, KH Kampert, B Keilhauer, E Kemp, RM Kieckhafer, HO Klages, M Kleifges, J Kleinfeller, R Knapik, J Knapp, D-H Koang, A Kopmann, A Krieger, O Krömer, D Kümpel, N Kunka, A Kusenko, G La Rosa, C Lachaud, BL Lago, D Lebrun, P Lebrun, J Lee, MA Leigui de Oliveira, A Letessier-Selvon, M Leuthold, I Lhenry-Yvon, R López, A Lopez Agüera, J Lozano Bahilo, MC Maccarone, C Macolino, S Maldera, M Malek, G Mancarella, ME Manceñido, D Mandat, P Mantsch, AG Mariazzi, IC Maris, D Martello, J Martínez, O Martínez Bravo, HJ Mathes, J Matthews, JAJ Matthews, G Matthiae, D Maurizio, PO Mazur, T McCauley, M McEwen, RR McNeil, MC Medina, G Medina-Tanco, A Meli, D Melo, E Menichetti, A Menschikov, Chr Meurer, R Meyhandan, MI Micheletti, G Miele, W Miller, S Mollerach, M Monasor, D Monnier Ragaigne, F Montanet, B Morales, C Morello, E Moreno, JC Moreno, C Morris, M Mostafá, MA Muller, R Mussa, G Navarra, JL Navarro, S Navas, L Nellen, C Newman-Holmes, D Newton, T Nguyen Thi, N Nierstenhöfer, D Nitz, D Nosek, L Nozka, J Oehlschläger, T Ohnuki, A Olinto, VM Olmos-Gilbaja, M Ortiz, S Ostapchenko, L Otero, D Pakk Selmi-Dei, M Palatka, J Pallotta, G Parente, E Parizot, S Parlati, S Pastor, M Patel, T Paul, V Pavlidou, K Payet, M Pech, J Pekala, R Pelayo, IM Pepe, L Perrone, S Petrera, P Petrinca, Y Petrov, Dieppham Ngoc, Dongpham Ngoc, TN Pham Thi, A Pichel, R Piegaia, T Pierog, M Pimenta, T Pinto, V Pirronello, O Pisanti, M Platino, J Pochon, TA Porter, P Privitera, M Prouza, EJ Quel, J Rautenberg, S Reucroft, B Revenu, FAS Rezende, J Rídky, S Riggi, M Risse, C Rivière, V Rizi, M Roberts, C Robledo, G Rodriguez, D Rodríguez Frías, J Rodriguez Martino, J Rodriguez Rojo, I Rodriguez-Cabo, G Ros, J Rosado, M Roth, B Rouillé-d'Orfeuil, E Roulet, AC Rovero, F Salamida, H Salazar, G Salina, F Sánchez, M Santander, CE Santo, EM Santos, F Sarazin, S Sarkar, R Sato, V Scherini, H Schieler, F Schmidt, T Schmidt, O Scholten, P Schovánek, F Schüssler, SJ Sciutto, M Scuderi, A Segreto, D Semikoz, M Settimo, RC Shellard, I Sidelnik, BB Siffert, G Sigl, N Smetniansky De Grande, A Smialkowski, R Smída, AGK Smith, BE Smith, GR Snow, P Sokolsky, P Sommers, J Sorokin, H Spinka, R Squartini, E Strazzeri, A Stutz, F Suarez, T Suomijärvi, AD Supanitsky, MS Sutherland, J Swain, Z Szadkowski, J Takahashi, A Tamashiro, A Tamburro, O Tascau, R Tcaciuc, D Thomas, R Ticona, J Tiffenberg, C Timmermans, W Tkaczyk, CJ Todero Peixoto, B Tomé, A Tonachini, D Torresi, P Travnicek, A Tripathi, G Tristram, D Tscherniakhovski, M Tueros, V Tunnicliffe, R Ulrich, M Unger, M Urban, JF Valdés Galicia, I Valiño, L Valore, AM van den Berg, V van Elewyck, RA Vázquez, D Veberic, A Veiga, A Velarde, T Venters, V Verzi, M Videla, L Villaseñor, S Vorobiov, L Voyvodic, H Wahlberg, O Wainberg, T Waldenmaier, P Walker, D Warner, AA Watson, S Westerhoff, G Wieczorek, L Wiencke, B Wilczynska, H Wilczynski, C Wileman, MG Winnick, H Wu, B Wundheiler, J Xu, T Yamamoto, P Younk, E Zas, D Zavrtanik, M Zavrtanik, A Zech, A Zepeda, M Ziolkowski, B Kégl

Abstract:

Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.